The present invention relates to drainage devices and systems and more particularly to suction drainage systems and devices for removing gases and/or liquids from medical patients, such as from the pleural cavity, by means of a pressure differential.
For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the xe2x80x9c3-bottle set-upxe2x80x9d which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient""s pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also usually prevents the back flow of air into the chest cavity.
Suction pressure is usually provided by a central vacuum supply in a hospital so as to permit withdrawal of fluids such as blood, water and gas from a patient""s pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient. Such suction pressure (vacuum) and pressure differentials must be precisely maintained because of the dangerous conditions which could result if unduly high or low pressure differentials should occur. However, the hospital suction source typically can vary over time which degrades the suction performance. Also, drainage systems incorporating manometers in the suction control chamber are inconvenient because of the need to add water prior to use, as well as because of their size and weight. In addition, evaporation in the suction control chamber results in suction pressure variations which must be corrected by the addition of more water thereby increasing the maintenance and monitoring time required in the use of such drainage systems.
Also various inefficiencies have existed in the 3-bottle set-up resulting from the many separate components and the large number (usually 16 or 17) of connections. Complications such as pneumothorax may result from the loss of the water seal in the water seal bottle if suction were temporarily disconnected, and undue build-ups of positive pressure could cause tension pneumothorax and possible mediastinal shift. Another serious shortcoming of the 3-bottle set-up is the possibility of incorrect connection and the time necessary to set the system up to monitor its operation.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system sold under the name xe2x80x9cPleur-evacxe2x80x9d(copyright) in 1966 by Deknatel Inc. U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and U.S. Pat. No. Re. 29,877 are directed to various aspects of the Pleur-evac(copyright) system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. A more detailed description of the need for and the proper use of chest drainage devices is presented in the Deknatel Inc. Pleur-evac(copyright) publication entitled xe2x80x9cPhysiology of the Chest and Thoracic Catheters; Chest Drainage Systems No. 1 of a series from Deknatelxe2x80x9d (1985) which is incorporated herein by reference.
Among the features of the Pleur-evac(copyright) system which provide its improved performance is a single, pre-formed, self-contained unit that embodies the 3-bottle techniques. The desired values of suction are generally established by the levels of water in the suction control chamber. These levels are filled according to specified values prior to the application of the system to the patient. A special valve referred to as the xe2x80x9cHigh Negativity Valvexe2x80x9d is included which is employed when the patient""s negativity becomes sufficient to threaten loss of the water seal. Also, a xe2x80x9cPositive Pressure Release Valvexe2x80x9d in the large arm of the water seal chamber works to prevent a tension pneumothorax when pressure in the large arm of the water seal exceeds a prescribed value because of suction malfunction, accidental clamping or occlusion of the suction tube. The Pleur-evac(copyright) system is disposable and helps in the battle to control cross-contamination.
Despite the advantages of the Pleur-evac(copyright) system over the 3-bottle set-up and the general acceptance of the device in the medical community, there remains a continuing need to improve the convenience and performance of chest drainage systems and to render such systems compact. As noted above, fluid filled suction control chambers are filled to levels specified by the physician prior to being connected to the patient and the hospital suction system. The levels of suction obtained by such a chest drainage system are somewhat limited by the size (e.g. height) of the chamber required to maintain such suction levels. For high levels of suction, the chamber height required would in some circumstances render the drainage system impractical. In addition, accuracy of such underwater drainage systems is limited in that the fluid chamber employed therein must be constantly monitored visually by observing the liquid level in the respective chambers. Even when gauges are used, they likewise must be constantly monitored. In either case, when the fluid in the chambers evaporates, suction variations can occur which require the addition of more water to compensate for the water loss. All such activity of course is time consuming and is labor intensive.
Because of the size of such devices, they usually present an obstruction between the patient and visitors and the medical staff. As such, it is not uncommon for the device to be knocked over thereby creating the potential for cross-contamination of fluids within the device. These devices, may include some mechanism to minimize cross-contamination if the device falls over on its back, however, there is no protection available if the device falls on its frontside. It is also possible for these units, when knocked over, to become damaged or broken. Because these devices are usually close to the floor when patients are being transported, e.g. between floors of a hospital, it is not uncommon to see a device get broken because they collided with floors, obstructions or when getting on/off elevators.
As a result, the medical staff must take extra care when using such devices so the devices are not inadvertently knocked over or damaged during transportation. If a device is damaged, the medical staff must stabilize the patient, replace the device and clean up the collected fluids that have spilled. This can become even more problematic if the device is being used to collect blood in an autotransfusion process. In addition to the medical staff dealing with the unwanted patient anxiety that may occur, dealing with damaged or broken drainage devices is costly, labor intensive and time consuming. The foregoing also applies to devices that have become cross-contaminated because they are typically replaced by the medical staff.
Other drainage systems or devices have been developed since the introduction of the above described underwater systems to address their perceived shortcomings. One type of drainage device since developed, such as that described in U.S. Pat. No. 5,300,050, uses a waterless pressure regulator as a means for controlling suction pressure and a water filled chamber to establish a seal, the patient seal, between the fluid collection chamber and the suction source. These devices, like the above-described underwater drainage systems, can be damaged during transportation of patients, create an obstruction, and can be knocked over. Also, although these devices may include some protection to minimize cross-contamination if knocked over on their backside, there is no protection if they fall forward.
Another type of drainage device, such as that described in U.S. Pat. Nos. 4,738,671, 4,715,856, 4,544,370, 4,747,844, includes a modulation valve to control the suction flow, and correspondingly the suction pressure being developed, and a one way valve that forms the seal between the suction source and the collection chamber (e.g. the patient seal). In these devices the collection chamber is disposed below the mechanisms for regulating the suction flow and pressure, the mechanism for establishing the patient seal, flow meters and the internal drain and suction lines. These units are complex and involve a large number of parts. Also, because of the direct communication between the seal valve and the collection chamber, the seal valve can come into contact with the collected fluid if the device falls over. These devices, like those described, create an obstruction, can be damaged during transportation of patients and can be knocked over.
Yet another type of device as shown in U.S. Pat. No. 4,605,400, uses a plurality of one way valves to control suction pressure and one, or two one-way valves in series, as a one-way seal between the suction source and the collection chamber. The collection chamber is located below the other controlling parts of the device. A trap is provided between the seal valve(s) and the collection chamber to collect any liquids inadvertently withdrawn through the suction line therebetween. However, there is no barrier between the one-way seal and the suction source and other parts of the device. Thus, if the device is knocked over, collected fluid can flow through and contaminate various parts of the device. Moreover, there is the potential for the collected fluid to be drawn into the suction system. As with the above-described devices, this device can be damaged during patient transport and create an obstruction that can lead to the unit being knocked over.
In sum, it is common for prior art devices to get knocked over, which can have adverse consequences, and for them to get damaged during patient transport. This creates an environment where the medical staff must exercise extra care to avoid unwanted consequences. It also creates a labor intensive, time consuming and expensive environment.
Accordingly, there is a need for an improved device or system as well as methods related thereto for removing gases and liquids from medical patients where suction pressure control and the collection chamber seal does not involve the use of liquids. Further, there is a need for an improved mechanism for venting the collection chamber that is more resistant to cross contamination than prior art devices and systems. Additionally, there is a need for improved devices that are compact in size and are resistant to overturning as compared to prior art devices.
The present invention features a novel device for draining gases and/or liquid from the body cavity of a patient. The drainage of liquid, blood, and/or gas from the body cavity is accomplished by establishing a pressure differential between the device and the body cavity to be drained.
Various aspects or features of the drainage device of the instant invention provide a number of benefits as compared to prior art devices. In particular, these features yield a device that is compact as compared to prior art devices and which is more resistant to being overturned as compared to present art devices. This reduces the likelihood of damaging the device during patient transport as well as making it less cumbersome for the medical staff to use (e.g., minimizes obstruction potential).
These features also minimize or avoid the potential for cross contamination within the device whether it is inadvertently knocked over onto its backside or frontside. Other features provide added security, provide multiple indications of suction pressure being developed in the device, and yield a device hanger that can be easily adjusted to fit a given support arrangement.
In a first aspect, a device according to the present invention includes a novel venting or flow path arrangement interposed between a collection chamber, in which fluid (e.g., blood) is accumulated and a one-way valve forming the patient seal. The flow path is arranged to prevent the fluids accumulating in the collection chamber from being communicated upstream to other parts of the device in the event the device falls onto its face or backside.
In particular embodiments, the venting arrangement includes an intermediate chamber positioned proximate the backside of the device and at least two flow passages. One flow passage fluidly couples the intermediate chamber and the collection chamber and another flow passage fluidly couples the intermediate chamber to the flow path going to the patient seal. In a preferred embodiment, two spaced flow passages fluidly couple the intermediate chambers and the collection chamber. These flow passages are also arranged to be essentially perpendicular to the front surface of the device, in a front-to-back type of relationship.
The intermediate chamber is configured with two compartments that are fluidly coupled by means of a stepped opening therebetween which forms a stepped surface. Each collection chamber flow passage forms an aperture in a surface of one compartment and the flow passage to/from the patient seal vent path forms an aperture in a surface of the other compartments. The surface having the collection chamber flow passage aperture(s) is configured so it is lower than the surface of the other compartment, when the device is on its frontside or face.
An opening is provided in each collection chamber flow passage that is in fluid communication with the collection chamber opening is preferably arranged so it lies above the maximum height of the fluid accumulated in the collection chamber, when the device is on its backside. Correspondingly, the length of each collection chamber flow passage and the height of the step, in the intermediate chamber stepped surface, are established so the high point of the stepped surface lies above the fluid level in the collection chamber when the device is on its frontside or face. In this way, accumulated fluid from the collection chamber is not cross-communicated upstream to other parts of the device, if the device is inadvertently knocked over onto its frontside or backside.
In a second aspect, a device of the present invention includes at least two chambers, a pressure regulation chamber and a collection chamber that are fluidly interconnected by a one-way valve that represents the patient seal. The one-way valve permits flow of gases from the collection chamber to the pressure regulation chamber and blocks flow of gases from the pressure regulation chamber to the collection chamber. The collection chamber also includes a port that is in fluid communication with the region to be drained.
The pressure regulation chamber includes two ports, both disposed upstream of the one-way valve, where one port is fluidly interconnected to a source of negative pressure (i.e., a suction source) and the other port is open to atmosphere. The drainage device further includes a suction pressure control mechanism that selectively adjusts the negative pressure being applied to the collection chamber and maintains the negative pressure being applied at or about the selected value. In particular embodiments, the suction pressure control mechanism includes a suction pressure control valve that is a spring loaded and spring operated valve disposed between the atmospheric and suction source ports. The spring is biased or loaded (e.g., tensioned) to any one of a number of predetermined values, each value being representative of a suction or negative pressure to be applied to the collection chamber. The spring also biases the valve so as to be in a closed position until the suction source pressure exceeds the selected applied suction pressure, at which point the suction pressure control valve opens so as to maintain the applied suction pressure at the selected value.
In a preferred embodiment, the one-way valve fluidly inter-connecting the pressure regulation chamber and the collection chamber, is a high precision flapper-type check valve. Such a check valve opens at relatively low differential pressures and functions completely independent of any fluid present in the collection chamber. In a particular embodiment, the check valve opens at a pressure differential of about 0.5 cm of H2O.
More particularly, the check valve includes a disk shaped resilient valve element mounted along the flow path of the valve to permit the flow in one direction only. The disk is maintained normally in a dish shape, with the dish disk being biased toward and against the valve inlet to normally bias the valve in a closed configuration. The operating characteristics of the valve, such as opening pressure and minimum flow rate, are adjustable by a disk mount. The valve also includes an outlet that minimizes back pressure to enable the valve to be quickly responsive even at low pressure differentials. In this way, a dry pressure seal is established between the pressure regulation chamber, the suction source and the collection chamber, which also permits gases being drained from a medical patient to be vented to the suction source while preventing gases from flowing into the collection chamber and correspondingly into the patient.
The waterless suction pressure control mechanism and the one-way valve cooperate so high differential suction pressures and a patient seal can be established in a highly compact and rugged device. The compactness results in a device less likely to be damaged during patient transport. The compactness of the shape also yields a device less likely to be knocked over or overturned while being used (e.g., when placed on the floor beneath a patient""s bed).
In a third aspect, a device of the instant invention further includes an air leak meter chamber fluidly interposed between the one-way valve and the collection chamber. The air leak meter chamber includes a fluid filled cavity and a means, responsive to gases flowing from the collection chamber to the suction source, that provides a relative indication of the flow rate of the flowing gases. In a particular embodiment, the indication means includes a downwardly sloping member having a plurality of spaced holes. The sloping member is in fluid communication with the collection chamber so the gases flowing from the collection chamber also can flow through the holes.
The holes and downwardly sloped member cooperate so the gas flowing through each hole is representative of a relative leakage rate. The sloping member also includes a plurality of vertical partitions that separate each of the spaced holes. The partitions provide a mechanism for clearly identifying the hole(s) gas is flowing through and correspondingly an indication of the relative flow rate. Preferably, the front panel of the device includes a transparent window to view the sloping member and the vertical partitions.
In a fourth aspect, a device of the instant invention includes a negative pressure indicator to sense the negative pressure being developed in the collection chamber. The negative pressure indicator includes a message post or board covered by a flexible membrane. The interior of the flexible membrane is fluidly coupled to the collection chamber so as to be responsive to the pressure changes in the collection chamber. Thus, when a negative pressure is established in the collection chamber, the flexible membrane collapses about the message board or post. When this occurs, the message and/or symbol on the message board becomes visible. A separate indication of collection chamber pressure can identify potential problems not otherwise indicated by a suction pressure indicator.
A fifth aspect of the invention features a novel hanger rotatably secured to the sides of the device so the device can be hung from the side rails of a hospital bed or other support mechanisms or structures (e.g. wheelchair). Each hanger includes a hook shaped attachment member having a flex point about which the hanger attachment member can be bent. The medical staff, e.g. nurse, can make local adjustments, e.g. side-to-side, to the hook shaped attachment member so it can accommodate variations in the support mechanism. An attachment to a support mechanism is not required, however, because the device also is configured to be self-supporting. In addition, the device shape and relative dimensions are established to lower the center of gravity in comparison to prior art drainage devices thereby improving the resistance of the device to overturning.
In a sixth aspect of the instant invention, the device is configured to continuously collect patient blood and reinfuse the collected blood back into the patient. More particularly, the collection chamber is configured to filter blood and collect the filtered blood in a portion of the chamber. Further, the portion of the chamber in which the blood is being collected includes sloping bottom surfaces to create a sump in which a drain port is located. This device is connected to a patient as described below so the blood can be re-infused into the patient.
Also featured is an autotransfusion drainage system using the above described drainage device, an attachment interface member and an external bag having a support structure. The interface member is configured to releasable engage attachments or mounts on the device and the framework of the external bag. Alternatively, the external bag can be configured to releasably engage the device attachments or mounts. The external bag also includes two ports/lines that communicate with he interior of the bag. One of the ports is connected to the drain line from the patient""s body cavity and the second port is connected to the drain port of the device. In this way, the fluid discharge from the medical patient is collected in the external bag. The external bag further includes a connection used to interconnect the external bag to an I.V. drip line or an I.V. infusion pump so a patient can be infused with the blood collected in the external bag.
The system further includes a filter medium that is preferably positioned so the blood being drained from the patient is filtered before it is collected in the external bag. Alternatively, the blood is collected and then filtered before it is transfused into the patient. In yet another embodiment, the blood being collected is filtered before collection and before transfusion into the patient. Similarly, the above-described alternate device embodiment, can be configured with a filter medium so the blood is filtered before collection, before transfusion or both.
The instant invention also features methods related to the use of the above described devices and systems including use in post operative environments.
The instant invention is most clearly understood with reference to the following definitions:
Autotransfusion shall be understood to mean the collection and the infusion of the collected patient""s blood back into the patient.